Watt-Level Continuous-Wave Emission from a Bifunctional Quantum Cascade Laser/Detector

Abstract

Bifunctional active regions, capable of light generation and detection at the same wavelength, allow a straightforward realization of the integrated mid-infrared photonics for sensing applications. Here, we present a high performance bifunctional device for 8 μm capable of 1 W single facet continuous wave emission at 15 °C. Apart from the general performance benefits, this enables sensing techniques which rely on continuous wave operation, for example, heterodyne detection, to be realized within a monolithic platform and demonstrates that bifunctional operation can be realized at longer wavelength, where wavelength matching becomes increasingly difficult and that the price to be paid in terms of performance is negligible. In laser operation, the device has the same or higher efficiency compared to the best lattice-matched QCLs without same wavelength detection capability, which is only 30% below the record achieved with strained material at this wavelength.

The Interband Cascade Laser

“…One can specially redesign the structure to perform both functions relatively well, but this dual functionality does not come without compromises. Specially designed QCLs and QCDs residing on the same native InP chip were first demonstrated to operate at λ ≈ 6.5 µm [221], later used to detect ethanol occupying a gap between the laser and detector [222], and subsequently optimized to produce up to 1 W of cw emission from the laser at 15 • C [223]. Hitaki et al avoided the wavelength mismatch issue by growing a separate QCD on top of the QCL, so that the design of each could be optimized independently [224].…”

Electronic structure robustness and design rules for 2D colloidal heterostructures

“…It is particularly known that smooth interfaces lead to some deviation of the quantum cascade laser spectrum with respect to the originally designed structure. 17 To model this effect in the case of II-VI semiconductor NPLs, we replace the abrupt profile by the following profile:…”

“…11 However, far less work has been focused on the investigation of their electronic structure 12,13 and, in particular, once heterostructures are grown. 14 This results from the lack of band structure parameters for II-VI semiconductor compounds that prevents advanced modelisation of those materials as it has been conducted for devices based on heterostructures of III-V materials (quantum well infrared photodetectors, 15,16 quantum cascade lasers, 17 and detectors 18 ).…”

Interband Cascade Photonic Integrated Circuits on Native III-V Chip

“…At zero bias, most electrons populate the extraction sub-band, so the QCD’s absorption peak occurs closer to ħω + ħω o than to the lasing energy ħω . Nonetheless, specially designed QCLs residing on the same native InP chip [ 8 ] with QCDs have produced up to 1 W of cw emission at 15 °C [ 34 ].…”